1B68

APOLIPOPROTEIN E4 (APOE4), 22K FRAGMENT


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2 Å
  • R-Value Free: 0.255 
  • R-Value Work: 0.200 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Interaction of the N-terminal domain of apolipoprotein E4 with heparin.

Dong, J.Peters-Libeu, C.A.Weisgraber, K.H.Segelke, B.W.Rupp, B.Capila, I.Hernaiz, M.J.LeBrun, L.A.Linhardt, R.J.

(2001) Biochemistry 40: 2826-2834


  • PubMed Abstract: 
  • Apolipoprotein E (apoE) is an important lipid-transport protein in human plasma and brain. It has three common isoforms (apoE2, apoE3, and apoE4). ApoE is a major genetic risk factor in heart disease and in neurodegenerative disease, including Alzhei ...

    Apolipoprotein E (apoE) is an important lipid-transport protein in human plasma and brain. It has three common isoforms (apoE2, apoE3, and apoE4). ApoE is a major genetic risk factor in heart disease and in neurodegenerative disease, including Alzheimer's disease. The interaction of apoE with heparan sulfate proteoglycans plays an important role in lipoprotein remnant uptake and likely in atherogenesis and Alzheimer's disease. Here we report our studies of the interaction of the N-terminal domain of apoE4 (residues 1-191), which contains the major heparin-binding site, with an enzymatically prepared heparin oligosaccharide. Identified by its high affinity for the N-terminal domain of apoE4, this oligosaccharide was determined to be an octasaccharide of the structure DeltaUAp2S(1-->[4)-alpha-D-GlcNpS6S(1-->4)-alpha-L-IdoAp2S(1-->](3)4)-alpha-D-GlcNpS6S by nuclear magnetic resonance spectroscopy, capillary electrophoresis, and polyacrylamide gel electrophoresis. Kinetic analysis of the interaction between the N-terminal apoE4 fragment and immobilized heparin by surface plasmon resonance yielded a K(d) of 150 nM. A similar binding constant (K(d) = 140 nM) was observed for the interaction between immobilized N-terminal apoE4 and the octasaccharide. Isothermal titration calorimetry revealed a K(d) of 75 nM for the interaction of the N-terminal apoE fragment and the octasaccharide with a binding stoichiometry of approximately 1:1. Using previous studies and molecular modeling, we propose a binding site for this octasaccharide in a basic residue-rich region of helix 4 of the N-terminal fragment. From the X-ray crystal structure of the N-terminal apoE4, we predicted that binding of the octasaccharide at this site would result in a change in intrinsic fluorescence. This prediction was confirmed experimentally by an observed increase in fluorescence intensity with octasaccharide binding corresponding to a K(d) of approximately 1 microM.


    Organizational Affiliation

    Gladstone Institute of Cardiovascular Disease, Cardiovascular Research Institute, and Department of Pathology, University of California, San Francisco, California 94941-9100, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
APOLIPOPROTEIN E
A
191Homo sapiensMutation(s): 0 
Gene Names: APOE
Find proteins for P02649 (Homo sapiens)
Go to Gene View: APOE
Go to UniProtKB:  P02649
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2 Å
  • R-Value Free: 0.255 
  • R-Value Work: 0.200 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 40.210α = 90.00
b = 53.210β = 90.00
c = 84.760γ = 90.00
Software Package:
Software NamePurpose
CCP4data scaling
X-PLORrefinement
CCP4model building
CCP4phasing
X-PLORmodel building
X-PLORphasing
MOSFLMdata reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2001-07-11
    Type: Initial release
  • Version 1.1: 2008-04-26
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance